1. Isotopes and Nuclear Reactions
Island of Stability

2. Isotopes
A variation of an element, that differs by the number of neutrons.
Protons CANNOT change – A proton is like an Atoms DNA, its what makes it an atom of a specific element
Electrons are so small – their mass is negligible to the mass of an atom
Neutrons are the only thing that can change – change the mass of the atom
When an atom varies in the number of neutrons, its mass also varies – these are called isotopes

3. Isotopic Notation How do we differentiate between different isotopes?
Isotopes can be written in a long format that uses the elements name and mass
Carbon – 12
Carbon – 13
Carbon - 14
Isotopes can be written with symbols just like elements can:

4. Practice with isotopic notation
Element
Isotopic Symbol
Mass Number
Atomic Number
Number of Protons
Number of Electrons
Number of Neutrons
Carbon – 14 14 6
14-6= 8
Polonium – 210
210 84
210-84= 126
Aluminum - 27 27 13
27-13= 14

5. Atomic Mass Recall what atomic mass is:
Average atomic mass is the mass of all the isotopes of an element combined
It is the mass given on the periodic table
It is calculated by taking the mass of each isotope of an element and multiplying each isotopes mass by its abundance then adding all the isotopes together.
(% of mass 1)(mass 1) + (% of mass 2)(mass 2) + (% of mass 3)(mass 3)…..
You would do this for each isotope of the element – some elements have many isotopes
Polonium has 25 isotopes and all are radioactive

6. Average Atomic Mass Problems:
Copper has two isotopes: 69.2% of all copper has a mass of 63 amu, while 30.8% of all copper has a mass of 65 AMU. What is copper’s average atomic mass?

7. Nuclear Chemistry
Radioactivity – the processes by which unstable nuclei achieve stability by releasing radiation
Radiation – the penetrating rays and particles emitted by a radioactive source
Radioactive Decay – the process in which unstable nuclei disintegrates
Radioisotopes – an isotope that has an unstable nucleus and undergoes radioactive decay

8. A reaction that results in a different nucleus
Nuclear Reactions
A reaction that results in a different nucleus
All reactions known up to this point, have not changed the nucleus
Law of Conservation of Mass
Nuclear reactions do not seem to follow this law.

9. Fission and Fusion Reactions
Nuclear decay that results from the nucleus of an atom splitting in to smaller pieces
Heavier atom becomes a lighter atom
The is nuclear energy on Earth
Requires little to no energy (usually)
Results in: free floating neutrons and photons (energy)
Nuclear reaction that results from two nuclei joining together to form one larger nucleus
Does NOT occur on Earth
If it did, it would solve our energy crisis
Releases gamma radiation for every reaction
This is what we could use for energy
Requires too much energy to start the reaction
Powers active stars

10. Fission and Fusion
Fission vs Fusion

11. Radiation Rays and particles emitted by the radioactive material
3 types
Alpha
Beta
gamma

12. Alpha Radiation Alpha particles are made of 2 protons and 2 neutrons
Has a +2 charge
The atomic mass decreases by 4 and the atomic # by 2
It is a VERY weak type of radiation
Can be stopped by paper or clothing
Limited to VERY large nuclei
Ex: Heavy Metals

13. Beta Radiation
Changes a neutron to a proton, emits fast moving electrons from the nucleus
-1 charge
Does not affect mass but increases the atomic number by 1
Can be stopped by: aluminum foil, thin pieces of wood

14. Gamma Radiation
High energy radiation wave of electromagnetic radiation given off by a radioisotope
Not a particle, but a wave of energy
NO charge
Released with alpha and beta radiation
Does NOT change the mass or atomic number
VERY hard to stop
Can only be stopped by thick concrete or lead

15. Homework Page 7 and 8 in your packets
We will complete page 9 together on Thursday – you may try it if you want